Good temperature coefficient of frequency SAW resonator on a SiO2/Al/LiNbO3 structure

This paper describes a good temperature coefficient of frequency (TCF) surface acoustic wave (SAW) resonator on a SiO 2 /Al/LiNbO 3 structure. We studied the dependence of TCF and electromechanical coupling factor (K 2 ) of shear-horizontal (SH) SAW on the SiO 2 thickness, where the SiO 2 shape control technique is applied to suppress spurious responses caused by Rayleigh-mode. As the results, we could realize high performance SAW resonator having moderate K 2 (8%) and zero TCF with complete suppression of the Rayleigh-mode spurious response. It was demonstrated that the SiO 2 shape control technique is effective for suppression of the Rayleigh-mode spurious response in the SAW resonator using the SiO 2 /Al/LiNbO 3 structure with wide range of SiO 2 thicknesses. We also revealed applicability of the SiO 2 /Al/LiNbO 3 structure to SAW duplexers with narrow duplex gap.